1. Field of the Invention
The present invention relates to an organic light-emitting device and an image display apparatus including pixels including organic light-emitting devices.
2. Description of the Related Art
Organic light-emitting devices each include an anode, a cathode, and a thin-film which contains a fluorescent organic compound and which is sandwiched between the anode and the cathode. Electrons and holes are injected into the thin-film from the cathode and the anode, respectively, whereby excitons are produced in the fluorescent organic compound. Light is emitted from the fluorescent organic compound when the excitons return to the ground state.
The organic light-emitting devices are referred to as organic electroluminescent devices or simply as organic EL devices.
In recent years, the organic light-emitting devices have been remarkably improved. Therefore, the organic light-emitting devices have high brightness at low voltage and fast response, emit light with various wavelengths, and can be transformed into thin, lightweight devices. This suggests that the organic light-emitting devices have various possible applications.
In the past, organic compounds for use in light-emitting devices have been extensively investigated. This is because light-emitting properties of an organic compound and the configuration of an organic light-emitting device affect the performance of the organic light-emitting device and therefore are important.
The following documents disclose materials for use in light-emitting layers and improvements in color purity of light-emitting devices: Japanese Patent Laid-Open Nos. 2000-323279, 2002-299058, 2004-206893, and 8-213174 and WO 00/39247.
Organic light-emitting devices disclosed in the above documents need to be improved for practical use.
In particular, these organic light-emitting devices need to emit brighter light or need to have higher conversion efficiency. Furthermore, these organic light-emitting devices need to be improved in durability so as not to be deteriorated with time for long periods or so as not to be deteriorated by atmospheric gases or humidity.
Organic light-emitting devices applied to full-color displays need to emit blue light with high color purity at high efficiency. However, this issue has not yet been satisfactorily resolved.
Therefore, the following compounds, devices, and techniques need to be designed: organic compounds having high color purity, luminous efficiency, and durability; organic light-emitting devices capable of efficiently using such organic light-emitting devices; and techniques for designing molecules for achieving such purposes.